New flexible aerogel can be used as magnetic sponge

Researchers have found a way to make an aerogel out of cellulose, a common …

Cellulose may have been around for millions of years, but that doesn't mean it can't teach a modern substance like aerogels a thing or two. A group of researchers have found a way to use cellulose to make a new type of aerogel that can be made flexible and absorbent like a sponge, or crushed into a sheet of "magnetic nanopaper." The aerogel's creators think both materials could find use in microfluidic devices.

By now, aerogels are sort of old news in the materials science community. Invented in 1931, the solids are famous for being light like styrofoam, but also highly porous and extremely rigid, capable of bearing weights many times their own. Although current forms have many uses, a group of scientists decided that overcoming their characteristic stiffness could open up a whole new range of uses.

When they looked for a material to use to circumvent the stiffness, the authors decided to try a type of cellulose. Cellulose, better known as "plants, mostly," is normally used to make products like paper and cardboard, but some forms of cellulose can also be quite strong—one type is thought to be three-quarters the strength of steel.

One of the best methods to make aerogel out of cellulose is to freeze-dry it, removing all moisture and leaving nothing but a web of pure, solid fibers. The gel is highly porous and mostly air at this point, and yet can still sustain a lot of weight.

Before they freeze dried the cellulose, the researchers first soaked it in a solution of two metal compounds, iron sulfate and cobalt chloride. While the cellulose soaked, tiny nanoparticles of the metals would stick to the cellulose and remain even after drying, so it could be used as a magnet if desired.

Once the cellulose was freeze dried into an aerogel, the researchers found it was capable of two different applications. One involved crushing most of the air out of it, resulting in a small, flat piece of magnetic "nanopaper" that could support four hundred thousand pounds per square inch.

But as a regular aerogel, its properties were still highly unusual: the aerogel was flexible and could bend in half and twist easily. Normally aerogels are brittle and fracture under too much force, but the cellulose version could stand twice as much strain as a regular aerogel.

The scientists found that they could also use the flexible aerogel as a tiny sponge. Because its volume was almost 99 percent air, it could absorb water and then be wrung out, while still retaining its shape and magnetic properties. A 60 milligram patch of aerogel could hold about a gram of water—not magical, but it does best the Sham-Wow.

So, has the sponge just been made over as magnetic and highly absorbent? In a way, yes. The very fine structure of cellulose aerogel will allow it to be used in tiny pieces while retaining their characteristics—very stiff and magnetic, or magnetic, flexible, and absorbent—depending on the properties needed.

The authors speculate that their aerogel could find wide use in materials science, as its components, especially the cellulose, come pretty cheap. In the future, it is likely to play the role of a tiny actuator, or appear in microfluidics devices used in fuel cells and for studying the physics of cells.

"resulting in a small, flat piece of magnetic "nanopaper" that could support four hundred thousand pounds per square inch."

I want to know more about this. I imagine that you could put 400,000 pounds on top of a sheet of paper and then take the weight back off and the paper would still look pretty much like a sheet of paper, but I wouldn't say that the paper "supported" the weight. I just can't picture what is happening here.

I must lack imagination. I saw "flexible aerogel" and immediately latched onto the idea of a superior insulation material for weatherizing our country's houses on the cheap.I mean, it's probably more expensive than fiberglass, but I bet it's a lot safer and less irritating, plus it's still an aerogel.

I'm wondering about that 400,000 lb. "support" claim myself - I could take that several different ways.

Magnetic aerogel - that's food for thought, especially if it's flexible and can be folded or flattened in a variety of ways. New technology for rapidly deploying safety systems, or contaminant capturing? Pretty neat.

I guess I should read further about this. Doesn't freeze drying mean that this would be susceptible to absorbing moisture out of the air and quickly becoming non-aerogel? Doesn't soaking up water also remove its aerogel properties? Unlike the other aerogel, wouldn't bone-dry cellulose be a horrible high-temp insulator (disappear in a flash of smoke when you did the blow-torch trick)?

I must lack imagination. I saw "flexible aerogel" and immediately latched onto the idea of a superior insulation material for weatherizing our country's houses on the cheap.I mean, it's probably more expensive than fiberglass, but I bet it's a lot safer and less irritating, plus it's still an aerogel.

Unfortunately, it's incredibly expensive. A few months ago I looked around and it appears that several companies are trying to get the manufacturing cost low enough to use as common insulation.

"resulting in a small, flat piece of magnetic "nanopaper" that could support four hundred thousand pounds per square inch."

I want to know more about this. I imagine that you could put 400,000 pounds on top of a sheet of paper and then take the weight back off and the paper would still look pretty much like a sheet of paper, but I wouldn't say that the paper "supported" the weight. I just can't picture what is happening here.

I imagine they're referring to tensile strength, measured by pulling the sheet apart until it rips, at which point this pulling force would = 400k lbs/sq. in. as opposed to the way it's done for solid materials, by applying the pressure from above, and measuring downward force required to fracture.

now imagine they figured out some way to roll this into a continuous cylinder/cable, and how much that would multiply the strength, I wonder how it would compare to those carbon nanotube type materials.

I must lack imagination. I saw "flexible aerogel" and immediately latched onto the idea of a superior insulation material for weatherizing our country's houses on the cheap.I mean, it's probably more expensive than fiberglass, but I bet it's a lot safer and less irritating, plus it's still an aerogel.

If one of the limits on long term space flight is exposure to micro metorites and electromagnetic radiation, wouldn't one application be as a two layer skin on spacecraft, using the outside thin layer to polarize the hull to deflect EMR and the gel layer to catch any objects that manage to penetrate the skin? Just saying as a non-scientist and SF fan.

They should just focus on getting the price down and the applications more widespread. Cars and airplanes would be a good industries that require lightweight strong materials. This flexible one would seem to be ideal, if it has the same insulative properties, in outdoor jackets, etc.

Aerogels have been hyped a lot, but frankly their applications in the consumer space almost non-existent it seems.

@new2mac: "Aerogel must be the coolest shit on Earth, EVER. They just never do anything with it."False. It was used as a collection medium for the STARDUST mission, which passed nearby a comet and gathered samples of its detritus.That wasn't on Earth, however, so your statement may be correct on a technicality.

They landed that sample back on earth so they could see what it had captured, is that statement is true.

Although I'd like to see aerogels, nanotubes, and buckyballs in a three-way battle royale for awesomest material.